<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <div class="wrap">
    <div class="main">
      <div class="inner">inner</div>
    </div>
    <div class="left">left</div>
    <div class="right">right</div>
  </div>
  <style>
    .wrap {
      overflow: hidden;
    }
    .main,
    .left,
    .right {
      float: left;
    }
    .main {
      width: 100%;
      background-color: red;
    }
    .left {
      width: 200px;
      margin-left: -100%;
      background-color: green;
    }
    .right {
      width: 100px;
      margin-left: -100px;
      background-color: blue;
    }
    .inner {
      margin-left: 200px;
      margin-right: 100px;
      background-color: darkgoldenrod;
    }
  </style>
</body>
</html>
